favorite novice transmitter for about $100 these days...

Discussion in '"Boat Anchor" & Classic Equipment' started by K9UR, Oct 23, 2021.

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  1. KX4OM

    KX4OM Ham Member QRZ Page

    I just bought a novice-class trumpet that is 63 years old. Same model I had as a that kind of "novice".

    Ted, KX4OM
     
  2. N2EY

    N2EY Ham Member QRZ Page

    Maybe.

    Your T-60 may be 60 years old, but how many of those years did it spend sitting unused on a shelf?

    $50 back then was a lot of money! Equivalent to over $300 today.

    Heathkit sold their DX-20 for $35.95. It included plate and grid current metering. There's no reason ANY "novice" transmitter should lack such metering.

    A new 6DQ6 wasn't cheap back then, either.

    Often what we learn is how NOT to do things.

    That said, the T-60 is a prime candidate for mods and upgrades that will make it a usable transmitter. All the big pieces are there.

    TNX for the CWT Q, btw.

    73 de Jim, N2EY
     
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  3. KM1H

    KM1H Ham Member QRZ Page

    I built a T-150A while aboard ship in the USN, worked fine 80-15 mostly CW, The RBC receiver didnt cover 10.
    Sold that and built another when shore based and had an apartment and made a few mods for VFO stability and 6M performance. For the price and the times it was well worth the money.

    Decades later I bought a used one, tweaked as before and used at our Maine summer home where space was tight. A highly modified also used Halli SX-140. Used mostly on AM including a lot of 6M and did well about a 1/4 mile from the ocean.

    Recently sold the pair and surprised at the price! Guess others still want them.

    Carl
     
  4. KW4H

    KW4H Platinum Subscriber Platinum Subscriber QRZ Page

    Your comment is on-target. I was born in '59, and most of the boat anchors I fiddle with predate that. I just love the old stuff. But I have to totally agree with you that what we often learn is how badly some equipment was designed "back in the day". It's not just electronic design issues, but sometimes physical design issues that make you scratch you head and wonder "why on earth would THAT have been put THERE?"

    Steve
     
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  5. N2EY

    N2EY Ham Member QRZ Page

    That's great!

    Yes.

    There are all sorts of reasons for poor designs:

    1) Cost. Often the designers had to meet a specific price.

    2) Available parts. In some cases the best-choice parts were simply unavailable, either due to shortages, long lead times, or price hikes. Or, the company had a warehouse full of certain parts or assemblies and the designers were told to use what the company had. In some cases, a "new" product was really an older design with a few minor changes.

    3) Deadlines. Sometimes it was decided that a product had to be in production by a certain date, resulting in a rushed design.

    4) Last minute changes and problem fixes. Sometimes a problem was discovered after a design was complete, or nearly so, resulting in odd-seeming fixes.

    5) Incompetence. Not all designers of the past knew what they were doing. Nor did they understand how the product would actually be used.

    In some cases, the shortcomings of a bad design can be easily fixed, while in others, fixing them requires radical changes and a lot of work.

    There are also differences in what was expected of a particular product at the time. For example, warm up drift and dial inaccuracy was expected in most amateur gear of the past. Good signal quality wasn't always guaranteed. Etc.

    I can supply some examples of the above if you're interested.

    73 de Jim, N2EY
     
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  6. KW4H

    KW4H Platinum Subscriber Platinum Subscriber QRZ Page

    I believe cost is/was the major factor. Back in the 80s I had a small business repairing VCRs and home stereo systems (I was also trained in TV repair, but hated working on them). There was always -- and I mean 100 percent of the time -- a direct correlation between the design and quality of the parts, and the cost of a unit. Depending upon the failure, some gear was so cheaply made I had no real option other than to tell the customer to throw it out and buy something else. It's because of the "cascade of failures" problem that's created when a poorly designed device begins to malfunction -- I could replace that failed output transistor, but when there are up to 10 or maybe 15 other crappy parts or a design flaw that caused the failure, it's just a matter of time before it blows up again. And again. Or both output transistors. Or the speaker switch made of swiss cheese breaks.

    One of the reasons why I like fixing up boat anchors is because prior to the solid-state era even the lower cost gear had some quality in it. I don't like fixing up junky-junk.

    73 - Steve, KW4H
     
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  7. AC0OB

    AC0OB Platinum Subscriber Platinum Subscriber QRZ Page

    Same here.

    Many people have poo-pooed the HT-40 and the Knight T-60 as a novice transmitter for having parasitic oscillations. Of the many that have come across my bench, I have never seen parasitic's on either my scope or my Spectrum Analyzer.

    Also notice that both transmitters use Pi-input circuits in the Final grid tuning.


    Pheel
     
  8. K9UR

    K9UR Subscriber QRZ Page

    Now QRV ! 8DC7BF1E-C69F-4F90-9587-2D35A2BC39B5.jpeg

    E9318453-94DD-47C2-AE46-D1D4D00BFE75.jpeg
     
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  9. W9BRD

    W9BRD Ham Member QRZ Page

    Parasitic oscillations were not necessarily built into their designs. What was built into their designs was poor subharmonic-output suppression -- 7 MHz output when you're using a 7-MHz crystal to get to 20 or 15, or instance. The reason for this is twofold: (a) the pi network commonly used between power amplifier and antenna in most tube-based ham gear from the HT-40/T-60 era and beyond is a peaked low-pass filter and (2) a mis-engineered low-pass driver-to-final coupling circuit (originated in somewhat-better-engineered form by George Grammer of ARRL in the early 1950s) that also affords essentially no subharmonic rejection between driver and final. Wireless Girl describes this problem in her HT-40 writeup at https://wireless-girl.com/Projects/AMTransmitters/HallicraftersHT40.html.
     
  10. AC0OB

    AC0OB Platinum Subscriber Platinum Subscriber QRZ Page

    So if say I am wanting to operate on 14.250 MHz with a 7.125 MHz base frequency set by a VFO, what is the level of the 7.125 MHz component in the output signal in terms of dB down from 14.250 MHz signal? You do realize that most doubler/tripler stages have to operate in deep Class C with the fundamental frequency given to them?

    What is your suggestion for an improved driver-to-final coupling circuit in say the HT-40?

    Janis' article, AB2RA, seems to indicate that most of the trashy VFO output signals were to blame and only the HA-5 VFO had a decent signal.



    Pheel
     

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